The present invention relates to a housing structure that is equipped with a lightning protective system, and particularly the equipping of a railroad switch house with a lightning protection system for maintaining the integrity of the electrical or electronic equipment stored therein.
Signal switch houses for railroads have been around for a long time. Such houses usually have stored therein electrical and/or electronic equipment and other electronic components such as for example relays for monitoring and regulating the operation of trains along railroad tracks to which such houses are adjacently located. Such switch houses are usually spaced anywhere from xc2xe to 1xc2xd miles all along the length of the railroad tracks. In essence, the equipment stored in the houses would provide wayside signals to the train, as for example red, yellow and green lights, so that the train engineer has some indication of the condition of the tracks down the line. Moreover, a switch house is usually located at each railroad crossing for providing warnings to traffic crossing the railroad tracks if a train is approaching.
The equipment stored inside each of these switch houses may vary, depending on the kinds of signals that are to be monitored and regulated. However, each of the equipment stored in each of the switch houses tends to be electrical or electronic in nature, and accordingly could be affected by power surges resulting from transients from the power line or lightenings that strike either the railroad tracks adjacent to the house or the house directly. And when the equipment malfunctions, the signals for regulating the movement of trains along the railroad tracks are disrupted.
It has been estimated that it costs a single railroad company thousands of dollars for each unscheduled train stop as the stoppage of one train tends to have a domino effect on all other trains along the same tracks. This is due to the fact when a train is stopped unexpectedly, the tracks would act as a shunt to prevent a proceed signal from being transmitted along the tracks to other switch houses. With the absence of the proceed signal, the equipment in the switch houses downstream or upstream of where the stopped train is would provide a caution yellow light or a stop red light to the train engineers at the other trains to warn them either to slow down or stop.
Prior to the instant invention, there has not been any reliable protection against power surges that may affect the performance of the electrical or electronic equipment in the switch houses. Thus, excessive lightning damage has been sustained by the train control equipment. Such damage not only means that the equipment has to be replaced, but more importantly it affects the operation of the trains along the tracks and therefore causes both inconvenience and a loss of money for the railroad companies.
The housing structure or house of the instant invention has secured to one of its interior walls a terminal board. Coupled to the terminal board are a number of terminal blocks or strips to which wires may be mounted. A number of openings are provided on the floor of the house for enabling wires external to the house to be inserted into the house. These outside wires are mounted to one of the terminal blocks on the terminal board. The equipment that are inside the house are placed on shelves which are secured to the house. The signal leads or wires that are provided to and from the equipment are also mounted to the terminal board, preferably at another terminal block or strip coupled to the terminal board. There is also coupled to the terminal board at least one conductive terminal strip that is electrically grounded. The wires from outside which are mounted to the terminal block on the terminal board each in turn are connected to the grounding strip by way of a current or lightning arrester. At least one ground plane is provided also on the terminal board so as to enable any power surges that may reach the terminal board to be readily routed to ground.
To confine any power surges that enter the house which most likely first reach the terminal board, a shield structure in the form of interconnected panels are placed over the terminal board so as to enclose at least the portion of the terminal board whereat both the wires from the outside and the wires that are connected to the equipment are located. The panels may be in the form of grids or solid sheets that are made of ferrous or non-ferrous metals. The panels furthermore are connected to ground. Thus, power surges that enter the house and wind up at the terminal board, even if they were to jump over the arresters that connect the outside wires to the terminal grounding strip, nonetheless are prevented by the shield structure from entering into the rest of the house. The power surges are therefore prevented from doing damage to the equipment stored in the house. The shield structure may be in the form of a Faraday cage.
To enhance grounding, in place of conventional grounding strips or terminals, the house of the instant invention utilizes a grounding strip that comprises a longitudinal U shaped member, with a longer side and a shorter side respectively up bending along the length of the member. Multiple holes are provided in the longer up-bent portion for enabling the grounding strip to be mounted to the terminal board. Notches or semicircular cut-outs are formed at the shorter up-bent side to enable the mounting thereto of the respective wires from the terminal block on the terminal board where the outside wires are mounted.
It is therefore an objective of the present invention to equip a house with lightening protection features.
It is another objective of the present invention to provide a Faraday cage inside a housing structure for confining power surges that may enter the structure.
It is still another objective of the present invention to protect equipment in a housing structure from lightning or power surges that may enter the structure.
It is yet a further objective of the present invention to provide to the terminal board of the house of the instant invention an inventive unitary grounding strip adaptable to be connected by a plurality of wires from the outside the house.